US Vice-President Joe Biden, center, poses with Afghan President Ashraf Ghani, left, and Pakistani Prime Minister Nawaz Sharif for the media prior to a meeting on the sidelines of the World Economic Forum in Davos, Switzerland, Thursday, Jan. 21, 2016. ... more >

Vice President Joseph R. Biden said Saturday that the U.S. and Turkey are prepared for a military solution in Syria if a political settlement isn’t possible, prompting an aide to clarify that he was referring only to the Islamic State terrorist group.

The latest round of Syria peace talks are scheduled to begin Monday in Geneva, although the session could be delayed in a dispute over the makeup of the opposition delegation.

After a meeting Saturday with Turkish Prime Minister Ahmet Davutoglu in Istanbul, Mr. Biden told reporters that they discussed how to resolve the long-running crisis in Syria.

“We do know that it would be better if we can reach a political solution, but we are prepared — we are prepared if that’s not possible to have a military solution to this operation and to taking out Daesh,” Mr. Biden said, according to a pool reporter traveling with him. Daesh is the pejorative Arabic acronym for the group of Islamic State insurgents, who hold parts of Syria.

The vice president’s office issued a transcript in which Mr. Biden was quoted as saying, “We are prepared if that’s not possible to make — to have a military solution to this operation in taking out Daesh.”

An aide to Mr. Biden later clarified that the vice president was talking about a military solution for the Islamic State, not Syria as a whole. The aide, who spoke on the condition of anonymity, said U.S. policy in Syria has not changed.

Mr. Biden said he and Mr. Davutoglu also discussed how the two NATO allies could further support Sunni Arab rebel forces fighting to oust Syrian President Bashar Assad. The goal, he said, is to prevent a separate state on the Turkish border after the U.S.-led coalition defeats the Islamic State.

Mr. Davutoglu said, “There should only be the legitimate Syrian opposition” represented in the peace talks. He said Turkey does not want representatives of the Islamic State, the militant group known as PKK or Mr. Assad’s military along the border.

“No ally, no friendly nation should expect us to sort of tolerate any armed forces other than the legitimate armed forces,” he said.

Mr. Biden said Saturday that the PKK, or Kurdistan Workers’ Party, is a threat to Turkey.

The Islamic State “is not the only existential threat to the people of Turkey. The PKK is equally a threat, and we are aware of that. It is a terror group, plain and simple, and what they continue to do is absolutely outrageous,” Mr. Biden said.